A wireless communication system is widely used to provide various types of communication services. For example, the wireless communication system provides voice and/or data services. The wireless communication system can use a frequency division duplex (FDD) scheme or a time division duplex (TDD) scheme. In the FDD scheme, uplink transmission and downlink transmission are achieved at the same time point while occupying different frequency bands. In the TDD scheme, uplink transmission and downlink transmission are achieved at different time points while occupying the same frequency band.
In order to effectively use limited radio resources in the wireless communication system, there are proposed methods and utilization for further effective transmission and reception in time, space, and frequency domains. Orthogonal frequency division multiplexing (OFDM) uses a plurality of orthogonal subcarriers. Further, the OFDM uses orthogonality between inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT). A transmitter transmits data by performing the IFFT. A receiver restores original data by performing the FFT on a received signal. The transmitter uses the IFFT to combine the plurality of subcarriers. The receiver uses the FFT to split the plurality of subcarriers. According to the OFDM, complexity of the receiver can be reduced in a frequency selective fading environment of a wideband channel, and spectral efficiency can be increased when selective scheduling is performed in a frequency domain by using a channel characteristic which is different from one subcarrier to another. Orthogonal frequency division multiple access (OFDMA) is an OFDM-based multiple access scheme. According to the OFDMA, efficiency of radio resources can be increased by allocating different subcarriers to multiple users.
The institute of electrical and electronics engineers (IEEE) 802.16 standard group was established in 1999 for broadband wireless access (BWA) standardization. The ‘WirelessMAN-OFDMA’ standard has recently been defined to use the OFDMA. The IEEE 802.16-2001 was approved in 2001, and is based on a physical layer of a single carrier (SC) called ‘WirelessMAN-SC’. The IEEE 802.16a standard was approved in 2003. In the IEEE 802.16a standard, ‘WirelessMAN-OFDM’ and ‘WirelessMAN-OFDMA’ are further added to the physical layer in addition to the ‘WirelessMAN-SC’. After completion of the IEEE 802.16a standard, the revised IEEE 802.16-2004 standard was approved in 2004. To correct bugs and errors of the IEEE 802.16-2004 standard, the IEEE 802.16-2004/Cor1 (hereinafter, IEEE 802.16e) was completed in 2005 in a format of ‘corrigendum’.
Recently, standardization on the IEEE 802.16m is in progress as a new technical standard based on the IEEE 802.16e. The IEEE 802.16m, which is a newly developed technical standard, has to be designed to support the previously designed IEEE 802.16e. That is, the newly designed system (i.e., IEEE 802.16m) has to be designed to effectively incorporate an operation of a legacy system (i.e., IEEE 802.16e). This is called backward compatibility.
Accordingly, there is a need to propose a frame structure of a new system supporting backward compatibility with a legacy system.